DESCRIPTION (Taken from the Investigator's Abstract) This proposed workshop is to convene 16 investigators representing 7 international, prospective lead-exposed cohorts for a meeting on September 23, 2000 to conduct a pooled analysis and examine lead-associated cognitive deficits below 10 micrograms per deciliter (mcg/dl). The preponderance of experimental and human data indicate that there are persistent, deleterious effects of low-level lead exposure on brain function, such as diminished intelligence. There is evidence that cognitive deficits associated with lead exposure occur below 10 mcg/dl, but the lowest blood lead concentration associated with adverse cognitive effects had not been defined. Each of the prospective studies have included too few children to examine any adverse effects of blood lead concentration < 10 mcg/dl. Collectively, however, there are over 1,500 children examined in the 7 prospective cohorts to be included in the pooled analyses. The objective of this proposed workshop and analyses is to test for evidence of cognitive deficits associated with blood lead concentrations below 10mcg/dl by pooling existing prospective cohorts. The conference will: 1. Review existing scientific literature that indicates lead-associated cognitive defects at blood lead concentrations below 10 mcg/dl. 2. Examine the relation of blood lead concentration and IQ (total, verbal and performance) for all children and for those who have blood lead concentrations at < 10 mcg/dl, < 5 mcg/dl, and < 2.5 mcg/dl. The workshop will be held in conjunction with the 18th International Neurotoxicology Conference in Colorado Springs, CO. The organizers will refine an analytic strategy to conduct the pooled analysis, develop a consensus about inclusion of variables, and define variables for comparison across studies. If the results of the proposed analyses show that lead-related cognitive deficits occur below 10 mcg/dl, it will provide evidence that argues for a reduction in blood lead levels considered "acceptable" - from 10mg/dl to 5mg/dl or lower. It would also argue for a shift toward the primary prevention of childhood lead exposure, which contrasts sharply with current efforts that rely almost exclusively on case management of children with elevated blood lead levels.